Buggy code:
public default GraphTraversal < S , Vertex > addInE ( final String edgeLabel , final String stepLabel , final Object ... propertyKeyValues ) { } public default GraphTraversal < S , Vertex > addOutE ( final String edgeLabel , final String stepLabel , final Object ... propertyKeyValues ) { } public default GraphTraversal < S , Vertex > addBothE ( final String edgeLabel , final String stepLabel , final Object ... propertyKeyValues ) { } public default GraphTraversal < S , E > timeLimit ( final long timeLimit ) { } public default GraphTraversal < S , E > tree ( final String sideEffectKey ) { } public default GraphTraversal < S , E > tree ( ) { } public default < V > GraphTraversal < S , E > sack ( final BiFunction < V , E , V > sackFunction ) { } public default < E2 extends Element , V > GraphTraversal < S , E2 > sack ( final BinaryOperator < V > sackOperator , final String elementPropertyKey ) { } public default GraphTraversal < S , E > store ( final String sideEffectKey ) { } public default GraphTraversal < S , E > store ( ) { } public default GraphTraversal < S , E > profile ( ) { } public default < M , E2 > GraphTraversal < S , E2 > branch ( final Function < Traverser < E > , M > function ) { } public default < M , E2 > GraphTraversal < S , E2 > branch ( final Traversal < ? , M > traversalFunction ) { } public default < M , E2 > GraphTraversal < S , E2 > choose ( final Function < E , M > choiceFunction ) { } public default < M , E2 > GraphTraversal < S , E2 > choose ( final Traversal < ? , M > traversalFunction ) { } public default < E2 > GraphTraversal < S , E2 > choose ( final Predicate < E > choosePredicate , final Traversal < ? , E2 > trueChoice , final Traversal < ? , E2 > falseChoice ) { } public default < M , E2 > GraphTraversal < S , E2 > choose ( final Traversal < ? , M > traversalPredicate , final Traversal < ? , E2 > trueChoice , final Traversal < ? , E2 > falseChoice ) { } public default < E2 > GraphTraversal < S , E2 > union ( final Traversal < ? , E2 > ... traversals ) { } public default GraphTraversal < S , E > repeat ( final Traversal < ? , E > repeatTraversal ) { } public default GraphTraversal < S , E > emit ( final Predicate < Traverser < E > > emitPredicate ) { } public default GraphTraversal < S , E > emit ( final Traversal < ? , ? > emitTraversal ) { } public default GraphTraversal < S , E > emit ( ) { } public default GraphTraversal < S , E > until ( final Predicate < Traverser < E > > untilPredicate ) { } public default GraphTraversal < S , E > until ( final Traversal < ? , ? > untilTraversal ) { } public default GraphTraversal < S , E > times ( final int maxLoops ) { } public default GraphTraversal < S , E > withSideEffect ( final String key , final Supplier supplier ) { } public default < A > GraphTraversal < S , E > withSack ( final Supplier < A > initialValue , final UnaryOperator < A > splitOperator ) { } public default < A > GraphTraversal < S , E > withSack ( final Supplier < A > initialValue ) { } public default GraphTraversal < S , E > withPath ( ) { } public default GraphTraversal < S , E > as ( final String stepLabel ) { } public default GraphTraversal < S , E > barrier ( ) { } public default GraphTraversal < S , E > by ( ) { <START_BUG> ( ( com . tinkerpop . gremlin . process . graph . marker . FunctionHolder ) ( this . asAdmin ( ) . getEndStep ( ) ) ) . addFunction ( Function . identity ( ) ) ; <END_BUG> return this ; } public default < V > GraphTraversal < S , E > by ( final Function < V , Object > functionProjection ) { } public default GraphTraversal < S , E > by ( final T tokenProjection ) { } public default GraphTraversal < S , E > by ( final String elementPropertyProjection ) { } public default GraphTraversal < S , E > by ( final Traversal < ? , ? > traversalLambda ) { } public default GraphTraversal < S , E > by ( final Comparator < E > comparator ) { } public default < V > GraphTraversal < S , E > by ( final Function < Element , V > elementFunctionProjection , final Comparator < V > elementFunctionValueComparator ) { } public default < V > GraphTraversal < S , E > by ( final T tokenProjection , final Comparator < V > tokenValueComparator ) { } public default < V > GraphTraversal < S , E > by ( final String elementPropertyProjection , final Comparator < V > propertyValueComparator ) { } public default < M , E2 > GraphTraversal < S , E > option ( final M pickToken , final Traversal < E , E2 > traversalOption ) { } public default < E2 > GraphTraversal < S , E > option ( final Traversal < E , E2 > traversalOption ) { } @ Override public default void remove ( ) { } }

Fix:
( ( FunctionHolder < ? , ? > ) ( this . asAdmin ( ) . getEndStep ( ) ) ) . addFunction ( Function . identity ( ) ) ;